I thought the Naxx loot rules worked pretty well, too.
In fairness, these rules really only applied to Naxx (where one night would see a full clear), as FPP existed before that. That said, since this will be a progressive raid instance, it may be ideal to tweak the system just a little, as Father suggested.
RTU (main spec) - Highest roll w/ fewest RTUs.
RTE - ("unofficial" FP raid, but gbank contributions?)
Shard - Highest roll (limit, or common courtesy - i.e., if you've won a shard, let others roll?)
Also, we should decide at what point to reset RTUs (reset each week, or each *wing (or however Ulduar is divided), etc... ), and if we'll have anyone track RTUs for the raid.
My two cents!